The Lava antenna would not be on my list of antennas to consider, due to build quality, poor durability, grossly exaggerated performance claims and price.
If you want to receive the Denver stations I'd suggest you use an antenna or combination of antennas with both UHF and High-VHF capability.
If I was in the same situation, I'd start with an Antennas Direct DB8E and an Antennacraft Y10713. The DB8E allows you to aim the two panels independently, so I'd try aiming one panel south and the other west. I'd point the Y10713 south, at the KUSA transmitter. I'd use an RCA TVPRAMP1R preamp which has inputs for both antennas... Though I would perform
this test before spending any money on the preamp. Don't use a preamp if you don't need it. If the unamplified antennas are able to deliver enough signal on their own, simply use an Antennas Direct UHF/VHF signal combiner instead of the preamp.